The most probable cause of a series of mysterious afflictions that sickened American spies and diplomats abroad in the past several years was radiofrequency energy, a type of radiation that includes microwaves, the National Academies of Sciences, Engineering, and Medicine has concluded in a report. The conclusion by a committee of 19 experts in medicine and other fields cited "directed, pulsed radiofrequency energy" as "the most plausible mechanism" to explain the illness, which came to be known as Havana syndrome. The report, which was commissioned by the State Department, provides the most definitive explanation yet of the illness that struck scores of government employees, first at the U.S. Embassy in Havana in 2016, and then in China and other countries. Many of the officers suffered from dizziness, fatigue, headaches, and loss of hearing, memory and balance, and some were forced into permanent retirement. C.I.A. officers visiting overseas stations also experienced similar symptoms. The new report reveals strong evidence that the incidents were the result of a malicious attack. It attributes the illnesses to "directed" and "pulsed" " rather than "continuous" " energy, implying that the victims' exposure was targeted and not the result of more common sources of microwave energy. It also said the committee found the immediate symptoms that patients reported ... were more consistent with a directed "attack" of radiofrequency energy.